The rings on the CRL Protruding Ring Style Back-to-Back Shower Door Knobs are raised above the surface. The Knob measures 1-1/2 inches (38 millimeters) in diameter and extends 1-9/16 inches (40 millimeters) from the surface. Knob is made of solid brass, in your choice of several beautiful color combinations, from High Contrast Colored Knobs or Same Color Rings.